Improving the crashworthiness of motor vehicles has long been the goal of automobile manufacturers and policymakers. In the United States, Federal Motor Vehicle Safety Standard (FMVSS) No. 208 was promulgated to encourage improved occupant responses to frontal impact events. In sum, FMVSS 208 presently requires that a simulated vehicle occupant experience head and thoracic de-accelerations and right and left femur loads within specified limits following a motor vehicle impact with a rigid barrier at an impact velocity of 35 MPH. Additionally, the National Highway and Traffic Administration conducts its New Car Assessment Program (NCAP), which reports the results of its testing to the public based on the testing conducted according to the procedures of FMVSS 208.
In view of such testing protocols, motor vehicle front end structures have been optimized to provide improved vehicle performance in such frontal impact events. That is, techniques have been adopted to absorb the kinetic energy from such frontal impacts and severity of the secondary impact that potentially occurs between the occupant and the interior components of the passenger compartment. In addition to engineered structures for front end components, such as the engine compartment, hood, fenders, and front wheel suspension, and undercarriage components, occupant restraint systems have been employed. Such occupant restraint systems include traditional seat belt systems, adaptive seat belt systems, padded instrument panels, padded knee bolsters and glove box doors, and airbag systems.
Airbag systems for use in motor vehicles are generally well-known in the art. Such airbag systems have been used within motor vehicle interiors to mitigate and reduce occupant impacts with motor vehicle interior components and structures, such as steering wheels, instrument panels, knee bolsters, glove boxes, side door panels, and body pillars. Airbag systems are designed to deploy substantially immediately upon detection of the impact event and stay inflated during at least the early phases of the impact event.
In the adoption of frontal impact airbags, however, it is sometimes necessary to utilize two separate airbags to restrain the occupant to obtain optimal test results within the specified criteria. In particular, in the case of the front seat passenger position, a first passenger airbag is often mounted in an upper portion of the instrument panel and, when inflated, engages the torso and head of the passenger. A separate second knee airbag may be mounted in a lower portion of the instrument panel and, when inflated, engages the lower extremities, in particular, the knees of the passenger, to reduce loading on the occupant's femurs. However, the use of a separate knee airbag incurs additional cost, complexity, and weight. For example, additional structural steel is required to attach the knee airbag to the instrument panel and provide appropriate reinforcement.
Further, designs of motor vehicle interiors, especially occupant compartments, are evolving toward increased space or roominess for the motor vehicle occupants. For example, it has been proposed to provide a single fixed front passenger seat displaced over 200 mm rearward from the traditional middle front seat adjustment position to accommodate front seat passengers of all sizes (5th percentile prototypical female occupant to the 95th percentile prototypical large male occupants). However, restraining such a wide range of potential front seat occupants over such a long distance from the instrument panel disposed in front of the occupant creates a challenge in designing a single conventional front passenger airbag mounted on the top of the instrument panel. That is, the airbag load/displacement characteristics required to adequately restrain an unbelted 5th percentile prototypical female are not the same as those required to adequately restrain an unbelted 50th percentile prototypical male in a 25 mph frontal impact. Hence, solutions for obtaining acceptable simulated occupant responses for a wide spectrum of motor vehicle occupants using a rearwardly fixed forward facing front passenger seat, without the use of a separate knee airbag, would be advantageous.
The airbag assembly disclosed herein particularly accomplishes the foregoing optimization of simulated occupant response to a frontal impact event by providing a dual chambered head, torso, and knees combo airbag which deploys in the event of a frontal collision and provides uniform ride down energy and protection for the front passenger's head, torso, and lower extremities.